In general, it is known that fossil fuels cause environmental pollution and have the limitation of estimating the amount thereof. Therefore, many efforts have been made to develop renewable energy that can be substituted for the fossil fuels in every country.
The renewable energy may be classified into new energy such as hydrogen, fuel cells, and coal gasification, and regenerative energy such as solar energy, wind power, waterpower, waste, sea, biomass, and subterranean heat. Recently, technologies for producing bio-oil using lignocellulose biomass have been actively conducted.
The bio-oil is a liquid fuel similar to a heavy oil produced by performing fast pyrolysis, high-temperature high-pressure hydrolysis, and the like with respect to lignocellulose biomass. Particularly, the fast pyrolysis is a pyrolysis technology having the highest yield of oil. However, the fast pyrolysis is a technology where accuracy is required since a very short reaction time is maintained, and a reaction temperature is in a relatively narrow range.
More specifically, in a method for preparing bio-oil using the fast pyrolysis, a high heat transfer rate is necessary at a reaction interface so as to increase the yield of the bio-oil. Therefore, the size of a material is necessarily decreased, and it is necessary to precisely control the reaction temperature and the temperature in a steam state to be maintained at 500° C. and 400 to 450° C., respectively. Also, the time at which a product exists in a steam state is necessarily controlled to be within about 2 seconds, and steam is necessarily cooled down in a short time. In addition, since char serves as a catalyst for decomposing a product in a steam state, it is necessary to rapidly separate and remove the char.
However, a fast pyrolysis technology that satisfies all of the aforementioned conditions is not put to practical use, and it is required to develop a system for preparing bio-oil using fast pyrolysis, in which the bio-oil can be prepared at a high yield.